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A2 Chemistry revision-Chemistry of Materials

1. The d block-transition metals
Transition metal- a d block element that forms at least one ion with a partially filled
sub-shell of d electrons
Physical properties compared to s-block metals:
i. D-block metals are also good conductors of heat and electricity
ii. They are…

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iv. Repeat the titration to obtain 3 concordant results
Iodine ­ thiosulfate titrations
Used to find the concentration of solutions of oxidising agents.
i. A known amount of oxidising agent reacts with excess acidified potassium iodide
ii. The iodine produced is then titrated against a standard solution of sodium…

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Barrier protection- (i.e. painting, oiling, greasing and using polymer coatings) prevents
oxygen and water coming into contact with iron and steel
Galvanising-covering steel with thin layer of protective zinc that oxidises. Stainless steel
contains chromium that oxidises, leaving a protective oxide layer.
Sacrificial protection-attaching blocks of a more reactive metal…

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Condensation polymerisation-monomers join together to give a polymer and a small
molecule (i.e. HCL or HO)
i. Polyesters- dicarboxylic acid + diol
ii. Polyamides- diamine + dicarboxylic acid
Structure of a typical polymer is a mixture of:
i. Crystalline regions -ordered
ii. Amorphous regions - random
Glassy state- the amorphous…

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bonds, therefore the chains will slide over each other less easily and the polymer will be
more rigid than polymers with large amorphous regions.
In amorphous regions the polymer chains do not pack closely together and the
intermolecular bonds are very weak, therefore polymer chains will slide over each other…

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Reaction mechanisms
i. By studying rate equations and orders we can deduce a mechanism for a reaction
ii. The rate equation for a reaction tells us which particles are involved in the rate
determining step.
iii. The rate determining step is the slowest step in a multi-step reaction.
12. Optical…

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ii. At high concentrations of substrate, the rate equation is rate = k [E] because all
the active sites have become saturated.
Hence the reaction is zero order with respect to the substrate
Enzymes are used as catalysts in industry because:
i. They are specific
ii. Work at low temperatures…


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